Drill bit



M. HOKANSON May 2, 1939.

DRILL BIT Filed Nov. 21, 1936 INVENTOR- ATTORNEY.

Patent ghee-ti m-1 gm e" n, mete min to an meet relates {to improvemeii'tsin'drill bits and has particuidrreferenc'e "to that class of bit illustrated in applications I Serial Numbers 20,418 end-107x63:

5 f the drill bits now used the crossor starbit" is the most'comnion." Wind! firnne thisftvneqt bit is a fast euttinr tity it'jnas's of disadvantages? -'Por-eitaniple it wears-very ra areplaced ihto' the noiet' rurtii'" iiexij Wk 'iefihwt metme p u eter entree whereas v. t tiits.altimeter 'atrlght m much.

may be reconditioned eef-mden i' 'reur A tirnes even when nriilingin 'theliardest "granite, is theprincipai object of the present invention.

A further obiect'o! the-invention is to provide 2 faster cutting jzio'nger wearingebit than heretofore know-n, one that will not rifle the hole 31":

A still further object Ioi' the present invention is to provide a drill bit having a imiform distribution of the cutting edge. and one which reams the hole as it cuts, these being two essential characteristics of a good bit.

Other objects and advantages of the invention will appear in the following description thereof.

Referring now to the accompanying drawing, forming part of thisapplication, and wherein like reference characters indicate like parts:

Figure 1. is a central vertical sectional view through a twin circle bit embodyingfimy present invention.

Figure 2 is a plan view of the face of the bit. F gure 8 is a section on the line H of, ure 2. Figure 4 is a side elevation of Figure 2. V

' The bit here illustrated is adapted to be screw threadedly applied to the end of the drill rod of a drilling machine, and the shank end of the body portion I of the bit is hollow and internally screw threaded as at 2 for this purpose. Axially through the remainder of the bit from thebaseotthescrew'threadedopeningtothe cutting or working face thereof is provided the relatively small bore 3 for the introduction of 5 water to the bottom of the hole for washing away g v angles' the'reto itbonverges metv mome e11 trtne di'sad most common bit nowfused-and to' furthermore mvide'e bit which may' berebiifiditloned'in'but a minute's andon theiob. and -onefthst the material cut by the' bit. thesame being count'ersunk' at its lowermost extremity.

In the cutting or working face of the bit are memes two cdncavitiesof cone shape, indicated at and 5,'one:upon either side of the axis of 5- the 'bit and diametrically opposite to each other. conical depressions are of such a size and depththat 1wereit not-for the bore' 8 they would meet beltan'gjentftoleach other at the axis of W tangentwith' the periphery or 10 met r fi fithe'cuttingjfaee; re-

bit being hf 'substantiaily elliptical the iiodyjportion .otjthe bit from the These conicaiQdepresslons forming the inner vwails' -oif "the editing edzesfres'uit in the latter 'edges and at the same angle thereof as that of the inner wall, preferably at substantially 45', 25

this being the angle shown in the drawing and maintained through the cutting face of the bit except at the opposite edges thereof where the circles of the cutting edges aretangent to the wall of the hole being drilled 30 Theprincipal improvement in the instant embodiment of the invention is the forming in one side of each cutting edge an arcuate or concave depression. This depression occurs on the following or rear side of each cutting edge in re- 35 spect to its rotation when at work, as illustrated at 6 in the drawing. The leading portion of each cuttihg'edge is shown at I. it being assumed that the rotation oi the bit when'in action is anticlockwise as viewing Figure 2. It will be noted 40 that the water conducting bore a in the bit head 'is countersunk as at 8, and the outer periphery drawing, and it is at one of these points upon the following side of each cutting edge where the inner terminus of the arcuately depressed portion 6 of its respective cutting edge terminotes, while the opposite termini of said depressed cutting edges 6 occurs in the we plane with the leading portion of said' cutting edge adjacent the outermost extremity thereof, and at which point there is the least reiniorcing outer wall for said cutting edge. This, it will be noted.

results lna much wider and extensive shoulder or outer reinforcing wall indicated at [0 for the depressed cutting edges. though not necessarily essential other than to provide for their sharpening by the same conical depression which sharpens the remainder of the cutting edge, and that as the leading portion of the cutting edges oi the bit wear away more of the depressed cutting edges will come into service and thereby materially lengthen the life of the bit. I

It will be understood that the cutting away or stepping in this manner of a portion oi! each cutting edge is primarily for the purpose of providing a sluiceway for the snails 'or cuttings of the bit, and in actual practice has proven to augment the efliclency of such a bit materially and to greatly surpass anything possible by a common cross bit of like diameter.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

1. A drill bit comprising a body portion having a working surface provided with a plurality oi substantially circular cutting edges, the followlng edge, relative to the direction of rotation of the bit, '0! each circular edge having a dc? pressing therein, and the remainder of each circolor edge being in a plane at right angles to the bit axis.

2. A drill bit comprising a body portion having an axially disposed fluid opening therethrough and a plurality or substantially circular cutting edges, the following edge, relative to the direction of rotation of the bit. oi each circular edge having a depression therein. said depressions extending'trorn approximately the axis or the bit to the periphery thereot, and the remalnder oi each'circular edge being in a plane at right angles to the bit axis.

3. A drill bitcoxnprising a unitary body portion having a working surface provided with a plurality of concayities forming equally sized and shaped continuous cutting edges, corresponding portions of each cutting edge of the bit having a depression therein, the remaining portions or each cutting edge being in a plane at right angles to the axis of the .bit.

4. A drill bit comprising a unitary body por tion for removable attachment to the end of a drill rod, and having a working surface provided m with a plurality of concavities forming equally GERTIFI GATE Patent Io. 2,156,287.

sized and shaped continuous cutting edges and means for the access 01' sluice water thereto, and a sluiceway in corresponding and symmetrical portions of each cutting edge, the remaining portions oi each cutting edge being in a plane at right angles to the axis of the bit,

5. A drill bit comprising a body portion having a working surface provided with a plurality of substantially circular cutting edges, each i'orming a substantially uninterrupted circuitbetween the center 01 the bit and the periphery thereof, the. following approximate hall of each cutting edge, relative to'the direction of rotation of the hit, being depressed from the plane of the remainder thereto, the remainder of each cutting edge being in a plane at right angles to the axis or the bit.

6. The combination with a drill bit having an axial bore therein and conical depressions in the working face thereof forming equally sized and spaced continuous cutting edges about the axis thereof, approximately one-halt of each cutting edge being cut-away to provide clearance for the escape of cuttings of the drill, the remainder. of each cutting edge being in a plane at right angles tothebitaxis. v

7. A drill bit having an axial bore therein. the working face thereof having formed therein a plurality of" conical depressions, equally. spaced about the axis of thebitand forming continuans cutting edges extending substantially 'between said bore and the periphery oi the bit,

characterized by approidniately one-half of each cutting edge being cut-away to provide tree passage therefrom oi thespalls cutby the bit, the remainder of each cutting edge being in a plane at right angles to the bit axis. v

8. A detachable pneumaticdrill bit having an axial bore, therein for the access of fluid for removing the cuttings oi; .theJbit; the; working face of said bit being provided with conical depressions forming substantially continuous cut:- ting edges extending substantially betweensaid bore and the periphery ot the bi ibbpmxiinately .one-hait or each cutting edge being cut-away to provide clearance for thepas'sageoi'rtfieicuttings' or the bltaway {F 31 thcworklng lace thereof. the remainingneilectige; cutting edges 7 beingin aplane at right an les tfi'ithe bit axis.

L MAR'I'IN ,HOKANSON.

or oomcrron. llay. 2; 1932.

mun noxaxson,

, It is hereby certified that error appears in the printed. specification or the above nimbered patent requiring correctionae follows: Page 2,!irat column, line 29-26, clalnl, for the word "depressing" read-depression; that-the and Letters Patent should be read with this-connection thereinthnt the some may conform to the record of the case thelate'nt Office.

' si ned and sealed th1s6th dayofJune, A. p, 19 9. I

( Seal l Henry Van Arsdale Acting "Commissioner ot Patents.

results lna much wider and extensive shoulder or outer reinforcing wall indicated at [0 for the depressed cutting edges. though not necessarily essential other than to provide for their sharpening by the same conical depression which sharpens the remainder of the cutting edge, and that as the leading portion of the cutting edges oi the bit wear away more of the depressed cutting edges will come into service and thereby materially lengthen the life of the bit. I

It will be understood that the cutting away or stepping in this manner of a portion oi! each cutting edge is primarily for the purpose of providing a sluiceway for the snails 'or cuttings of the bit, and in actual practice has proven to augment the efliclency of such a bit materially and to greatly surpass anything possible by a common cross bit of like diameter.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

1. A drill bit comprising a body portion having a working surface provided with a plurality oi substantially circular cutting edges, the followlng edge, relative to the direction of rotation of the bit, '0! each circular edge having a dc? pressing therein, and the remainder of each circolor edge being in a plane at right angles to the bit axis.

2. A drill bit comprising a body portion having an axially disposed fluid opening therethrough and a plurality or substantially circular cutting edges, the following edge, relative to the direction of rotation of the bit. oi each circular edge having a depression therein. said depressions extending'trorn approximately the axis or the bit to the periphery thereot, and the remalnder oi each'circular edge being in a plane at right angles to the bit axis.

3. A drill bitcoxnprising a unitary body portion having a working surface provided with a plurality of concayities forming equally sized and shaped continuous cutting edges, corresponding portions of each cutting edge of the bit having a depression therein, the remaining portions or each cutting edge being in a plane at right angles to the axis of the .bit.

4. A drill bit comprising a unitary body por tion for removable attachment to the end of a drill rod, and having a working surface provided m with a plurality of concavities forming equally GERTIFI GATE Patent Io. 2,156,287.

sized and shaped continuous cutting edges and means for the access 01' sluice water thereto, and a sluiceway in corresponding and symmetrical portions of each cutting edge, the remaining portions oi each cutting edge being in a plane at right angles to the axis of the bit,

5. A drill bit comprising a body portion having a working surface provided with a plurality of substantially circular cutting edges, each i'orming a substantially uninterrupted circuitbetween the center 01 the bit and the periphery thereof, the. following approximate hall of each cutting edge, relative to'the direction of rotation of the hit, being depressed from the plane of the remainder thereto, the remainder of each cutting edge being in a plane at right angles to the axis or the bit.

6. The combination with a drill bit having an axial bore therein and conical depressions in the working face thereof forming equally sized and spaced continuous cutting edges about the axis thereof, approximately one-halt of each cutting edge being cut-away to provide clearance for the escape of cuttings of the drill, the remainder. of each cutting edge being in a plane at right angles tothebitaxis. v

7. A drill bit having an axial bore therein. the working face thereof having formed therein a plurality of" conical depressions, equally. spaced about the axis of thebitand forming continuans cutting edges extending substantially 'between said bore and the periphery oi the bit,

characterized by approidniately one-half of each cutting edge being cut-away to provide tree passage therefrom oi thespalls cutby the bit, the remainder of each cutting edge being in a plane at right angles to the bit axis. v

8. A detachable pneumaticdrill bit having an axial bore, therein for the access of fluid for removing the cuttings oi; .theJbit; the; working face of said bit being provided with conical depressions forming substantially continuous cut:- ting edges extending substantially betweensaid bore and the periphery ot the bi ibbpmxiinately .one-hait or each cutting edge being cut-away to provide clearance for thepas'sageoi'rtfieicuttings' or the bltaway {F 31 thcworklng lace thereof. the remainingneilectige; cutting edges 7 beingin aplane at right an les tfi'ithe bit axis.

L MAR'I'IN ,HOKANSON.

or oomcrron. llay. 2; 1932.

mun noxaxson,

, It is hereby certified that error appears in the printed. specification or the above nimbered patent requiring correctionae follows: Page 2,!irat column, line 29-26, clalnl, for the word "depressing" read-depression; that-the and Letters Patent should be read with this-connection thereinthnt the some may conform to the record of the case thelate'nt Office.

' si ned and sealed th1s6th dayofJune, A. p, 19 9. I

( Seal l Henry Van Arsdale Acting "Commissioner ot Patents. 

